Several compounds close to these compounds concerning both their type of activity and chemical structure, have been described in the British patent specification No. 2,096,999. One of the most effective compounds claimed in this cited patent specification was found to be 4-oxo-4-(3,4,5-trimethoxyphenyl)butenoic acid prepared by dehydrating the product obtained from the aldol condensation of 3,4,5-trimethoxyacetophenone with glyoxylic acid. The yield of the aldol reaction amounted to 28%, that of the dehydration to 71%, which means a total yield of only 20%.